Aortic Arches - Embryology in 3 minutes

Aortic Arches Development

Overview of Aortic Arches

• The embryo has two primitive aortas, right and left, consisting of three parts: the ventral aorta, dorsal aorta, and the arch connecting them.

• As development progresses, the ventral aorta fuses to form the aortic sac, which has right and left horns from which the aortic arches arise.

Formation of Aortic Arches

• The aortic sac is located superior to the truncus arteriosus of the heart tube; it gives rise to multiple pairs of aortic arches (first through sixth).

• The fifth arch may either not form or regress completely; while the first arch disappears but leaves remnants that contribute to maxillary artery formation.

Specific Aortic Arch Contributions

• The second arch vanishes with its remnants forming hyoid and stapedial arteries; third arch develops into common carotid arteries and part of internal carotid arteries.

• External carotid artery arises from sprouting off the third arch; meanwhile, portions between third and fourth arches disappear leading to distal internal carotid artery formation.

Right and Left Fourth Aortic Arches

• The right fourth aortic arch contributes to proximal right subclavian artery formation while its distal part is formed by segments of right dorsal aorta.

• The left fourth arch along with its horn forms the arch of aorta connected with left dorsal aorta; left subclavian artery originates from left seventh intersegmental artery.

Sixth Aortic Arch Development

• Known as pulmonary arch, it gives rise to pulmonary arteries where distal portions develop from buds growing into lungs while proximal parts derive from sixth arch's proximal section.

• On the right side, distal portion regresses whereas on the left side it persists as ductus arteriosus after truncus arteriosus partitioning occurs during heart development shifts.

Conclusion on Aortic Arch Development

• As development concludes, notable shifts occur such as higher origin for left subclavian artery near that of left common carotid artery completing overall development process for these structures.